Relief-valve for pneumatic tires.



"-R. F. TIBBETTS.

RELIEF VALVE FOB PNEUMATIC TIRES.

APPLICATION FILED DECJ, 19H.

Patented Apr. 27, 1915.

l WII /II IQ: .II/ IIIII I IIII II I I MII I I m l I I I WIW/Igx* r .1- aN IIII II I III IIII.IIII

RAYMOND F. TIBBETTS, OFMILWAUKEE, WISCONSIN, ASSIGNOR OF ONE-HALF T0 'EDWARD FIEBRICH, 0F RACINE, WISCONSIN.

RELIEF-VALVE FOR PNUMATIC TIRES.

Specica-tiox1A of Letters Patent.

Patented Apr. 27, 1915.

- Appiicatin med neember 7,1914. serial 11a-'sisma Toall whom it may concern:

Be it known that I, RAYMOND Fi 'I"1i3.ia'1"rs,'` a citizen of the United States, andresident of. Milwaukee, in 'the countyl -o'f *Milwaukee* and State of Wisconsn','have'inventediiew and useful Improvements "in Reli-efLValves Yfor Pneumatic Tires, of which' 'thelfol-lowing is a description, reference beingShad-to the escape 'ofair When-the"pressure"withinv the tire becomes abnormal as by the increase thereof due to the air becoming heated either by the friction ofvthe tire itself or by the ,action of the sun, such increase in pressure serving tomove the charging valve until its valve stem is depressed Iby engaging an obstruction, thus permitting the air to escape until a pre-determinedl normal pressure is attained. i

Another object of the invention is to provide such a. relief valve for pneumatic tires which will be sensitive to a gradual increase in pressure but which will be unaffected by a sudden increase in pressure as upon a tire forcibly strikmg a rock or other obstruction in the Another object of the invention is to provide such arelief valve with an adjustable cap which may be positioned'on the valve casing according to the maximum pressure desired for the tire according to a scale appearing on the valve casing and when so positioned serving to open the valve to relieve the air pressure when the air pressure reaches amount.

With the above and other objects in view (he invention consists in the relief valve for pneumatic tires as herein claimed and all equivalents. Y Y

Referring to the accompanying drawings in which like characters of reference indicate the same parts in different views: Figure 1 is a longitudinal sectional viewof a relief valve for pneumatic tires constructed in-accordance with this invention, the parts being in their normal condition; and Fig. 2 is a simllar view with parts in elevation and showing the valve in the act of being-re leased under abnormal pressure.

such pre-determined maximum `xin these drawings 10 indicates a vehicle tire engaged with a Wheel rim 11 as usual and containing an inner inflatable tube12 with a valve connection 13 of common con- --lstruction. The valve connection 13 however instead of forming the valve casing as usual terminates in a bulb like tube connection 14 and is'providedA with screw threads upon which the valve casing 15 is threaded.

:Jamnuts 16 are threaded on the outside ofthevalv'e casing 15 and clamped against the l. wooden wlieel Aitelly.

A valve tube 17 is slidably mounted in the lend lofthe valve casing 15 and is held against Vturning therein by means of a set screw 18 engaging a keyway 19 in the valve tube, said valve tube containing an ordinary charging valve 20 or check valve commonly known as the Schraeder valve. The lower end of the valve tube 17 has a bulb like tube connection 21 like the connection 14 and upon these two connections are fittedthe ends of a rubber .sure of the air within the tire so as to be capable of elongation and lateral distention.

4A series of grooves 23 are formed in the interior of the valve casing 15 to form detaining pockets into which the rubber tube 22 expands by its lateral distention when the tire is subjected to abnormal pressure. These detaining grooves retard the elongation of the tube 22, but the increase of pressure in the tire serves to force the valve tube 17 outwardly until the valve stem 20 carried thereby engages a cap 24 which slidably fits on the valve casing 15 and is held in its adjustments thereon by means of a set screw 25, such adjustments being determined by a scale of graduation marks 26 on the valve casing 15 indicating the maximum pressure of the tire at which the valve stem 20 engages the interior of the cap 24 to releaseA This relief of air only takes place upon the attainment of the abnormal pressure gradually, upon a sudden increase of pressure as when the tire strikes an obstruction in the road the resistance to the longitudinal exten#v sion of the rubber tube 22 caused by its filling in the annular grooves 23 ofthe valve casing retards its elongation until after such sudden increase in pressure has subsided.

What I claim as new and desire to secure by Letters Patent is:

1. A relief valve for pneumatic tires, comprising an elastic tube, means for connecting one end of the tube with the interior of a pneumatic tire, a valve mechanism connected with the other end of the elastic tube and movable therewith by the elongation of the elastic tube under abnormal pressure, said valve mechanism having a projecting `valve stem, means in the path of. the valve stem to be engaged thereby for opening the valve, and a casing surrounding the elastic, tube having a roughened surface to be engaged a casing Surrounding the elastic tube, a cap' on the casing to be engaged by the valve' stem for unseating the valve when the elastic tube becomes elongated under abnormal pressure, said casing having a series of grooves upon its inner surface to have the elastic tube it therein by lateral distention thereof under abnormal pressure and so retard elongation of the elastic tube. j In testimony whereof, I aflix my signature, in presence of two witnesses f RAYMOND F. TIBBETTS. Witnesses:

-R. S. C. CALDWELL, KATHERINE Hour. 

